When heaters are on, engine temp drops right to the bottom?

[VTI_EG_DAN]

hey all

When I heaters are on after engine has warmed up for 15 mins or so, engine temp drops right to the bottom?


any one know what this is?

 

[cyek9]

thermostat.

 

[alexb]

Well I hope I'm not telling you something you already know, but the heater matrix uses engine coolant to heat the air for the cabin, so it'll be exchanging heat from one to the other and therefore lowering coolant temp. I used to have to put my RX-7 heater on hot to help keep water temps normal-ish when I was on track

But as for it dropping right to the bottom that sounds a bit extreme, I'd go out and check my car but I don't fancy having the heaters on full hot today

Cheers,
Alex

 

[b16 mini]

where does your temp gauge needle usually sit when driving normally?
most likely thermostat.
sometimes you cant see anything wrong with them but there is, and the putting them in boiling water test is a waste of time,

 

[J700OCK]

had this problem and was thermostat give it a try easy and cheap job anyway